The aim is chemotherapy of diseases caused by Trypanosomatidae i.e., trypanosomiases and leishmaniases. The requisite lead compounds appear to comprise diverse compounds curing mice infected with a virulent Trypanosoma brucei. The compounds include antipolyamines (polyamines strongly chelate Cu) and chelators preferentially binding Fe(III). The curative chelators (the antipolyamines are at best weak chelators) were selected from two sequential in vitro screens: a) a growth system based on heme-sparing activity for Crithidia, b) killing of suspensions of bloodstream T. brucei obtained from rats. This was followed by trials with model infections in mice. The proposed work centers, on one hand, to extending the screen to include additional chelators, as suggested by results with mice and, on the other hand, improving the individual screening steps to make realistic use of more lipophilic candidate drugs, since permeating through host and parasite membranes is favored by lipophilicity. This consideration may be crucial for killing the intracellular forms of T. cruzi and Leishmania. Likewise, penetration of the blood-brain barrier would favor cures of late stages of African trypanosomiasis. The measures tried would include development of physiologically minimal media, i.e., no excess of metabolites, for two isolates of Crithidia growing at 37 C, replacing the serum in the suspension vehicle for T. brucei cells, and developing means of ensuring sustained release of drugs in the mouse model.